1. Field of the Invention
The present invention relates to a multiple cylinder rotary compressor, and particularly to a multiple cylinder rotary compressor in which a capacity control is effected in response to a fluctuating load.
2. Description of the Prior Art
Heretofore, such an apparatus of the multiple cylinder rotary compressor type, as shown in FIGS. 1 and 2, has been proposed. However, such rotary compressor has various disadvantages as describes hereinbelow. Namely, in FIGS. 1 and 2, a driving shaft 1 has eccentric portions 1a and 1b, and cylinders 2a and 2b define compression spaces 3a and 3b being concentric with respect to the driving shaft 1 on the inner peripheral portions thereof. Rolling pistons 4a and 4b are driven by means of the eccentric portions 1a and 1b of the driving shaft 1 and roll along the inner peripheral walls of the cylinders 2a and 2b, respectively. Plate type vanes 5a and 5b urge the outer peripheral portions of the rolling pistons 4a and 4b in their axial directions and partition the compression spaces 3a and 3b into low-pressure and high-pressure sides. The vanes 5a and 5b mounted within the cylinders 2a and 2b are urged by means of springs 6a and 6b, respectively. A driving side plate 7 closes the driving side of the compression space 3a and at the same time, is supported on the driving shaft 1 through a bearing (not shown). On the other hand, an anti-driving side plate 8 closes the anti-driving side of the compression space 3b and at the same time, is supported on the driving shaft 1 through a bearing. A partition plate 9 isolates the compression spaces 3a and 3b from one another and closes openings thereof, respectively. A closed container 10 contains the compression elements as described hereinabove. A low-pressure gas suction pipe 11 supplies a low-pressure refrigerant gas to low-pressure parts of the compression spaces 3a and 3b.
Operation of the conventional rotary compressor as mentioned above will be described hereinbelow.
The rolling pistons 4a and 4b roll along the inner peripheral walls of the cylinders 2a and 2b in response to the rotation of the driving shaft 1. As the result, a low-pressure refrigerant gas is sucked into the low-pressure parts of the compression spaces 3a and 3b through the low-pressure suction pipe 11 to be compressed therein. Consequently such gas is fed to a refrigerating circuit disposed outside the closed container 10 from a high-pressure discharge pipe (not shown) as a refrigerant gas at a high temperature and high pressure. In this refrigerating circuit, the refrigerant gas at a high temperature and high pressure cools a load to be cooled thereby to discharge the energy. Thus, such refrigerant gas is converted to the one at a low temperature and low pressure, the resulting refrigerant gas is refluxed to the low-pressure gas suction pipe 11, and the same operation is again repeated, whereby cooling for the cooling load to be cooled is continued.
However, there is such a disadvantage in the conventional rotary compressor as mentioned above that in the case where rotation of the driving shaft is variable, e.g., a driving shaft for motorcars or the like, when the rotation of the driving shaft increases, a discharge of the refrigerant per unit time also increases so that it results in overcooling. Furthermore, there are also such disadvantages in the case where a rotational frequency of the driving shaft is constant that if atmospheric temperature is relatively low, it results in overcooling so that extra power is used wastefully and an ON-OFF frequency increases to bring about uncomfortableness in the car interior.